Everyday fare, Daily bread = Very good translations, true-to-meaning of "commonplace" or "habitual", which is the only implication of "el pan nuestro de cada día", and also maintain the food reference. Personally, I believe everyday fare is more frequently heard/used, but this could be regional.
Staple = Could work, but does alter the meaning somewhat, because in addition to being common, it implies a degree of dependence, which is not the case in the Spanish expression. Bad things (like marital arguments) can also be "el pan de cada día".
Bread and butter = Really has nothing to do with the Spanish phrase at all, implying a financial dependence on a profit-making activity or item. In this example, it doesn't apply, nor can I think of one when it could be used as a translation for "el pan nuestro de cada día", although it could be used for "nuestro pan", so careful not to confuse the two.